When a jet-powered aircraft lands, the aircraft brakes, various aerodynamic drag sources (e.g., flaps, spoilers, etc.), and, in many instances, aircraft thrust reversers, are used to slow the aircraft down in the desired amount of runway distance. Once the aircraft is sufficiently slowed, and is taxiing from the runway toward its ground destination, the aircraft brakes are used slow the aircraft, and bring it to a stop at its final ground destination.
Presently, many aircraft brake systems include a plurality of hydraulic or electromechanical actuators, and a plurality of wheel mounted brakes. The brakes in many aircraft are implemented as multi-disk brakes, which include a plurality of stator disks and rotor disks. The stator disks and rotor disks may be alternately splined to a torque tube or wheel rim, and disposed parallel to one another, to form a brake stack. The actuators, in response to an appropriate pilot-initiated command, move between an engage position and a disengage position. In the engage position, the actuators each engage a brake stack, moving the brake disks into engagement with one another, to thereby generate the desired braking force.
As was noted above, the actuators used in some aircraft brake systems may be electromechanical actuators. An electromechanical actuator typically includes an electric motor and an actuator. The electric motor may supply a rotational drive force to the actuator, which converts the rotational drive force to translational motion, and thereby translate, for example, between a brake engage position and a brake disengage position.
When the aircraft is taxiing and has to be held against idle engine thrust, the pilot may need to apply the brakes for extended periods of time. Current electric brake implementations do not have a mechanism to limit the commanded force on the brake stack or prevent the pilot from applying high brake forces for indefinite periods of time. As a result, the motors and associated motor controllers are typically oversized.
Hence, there is a need for a system and method for minimizing the duty cycle of the electric actuators in aircraft electric brake systems. The present invention addresses at least this need.